program crashes without error

[dreamdelerium]

hi everyone. im really in the need of some help here. if someone could look over this code and see any problems, please let me know. heres the issue im having, when the program starts, it runs just fine. but if left running, after about 20 minutes, the program crashes, with no errors (the vista error pops saying the program has stopped working and windows is collecting information). if i run the program in the debug mode, it seems fine.
some background: when the program loads, its spawns a class to check a device connected to a comport for status changes. when finished, it spawns again and again until the program closes. heres the code i have:

<Microsoft.VisualBasic.ComClass()> <System.Serializable()> Public Class Form1
Private WC As Class2
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       
..onload event of the main form
.... other stuff that i dont think i a problem
....if i remove this bit, the program runs fine

        WC = New Class2

        ThreadPool.QueueUserWorkItem(AddressOf WC.FindMyPort)
        WC.Mycontinue = True

errorhandler:
        If Err.Number = 0 Then
        ElseIf Err.Number = 5 Then
        Else
            MsgBox(Err.Description)
        End If

    End Sub

end class

class two code:

Option Compare Text
Imports System.Windows.Forms
Imports System.Data.OleDb
Imports System
Imports System.Data
Imports GsmComm.GsmCommunication
Imports GsmComm.PduConverter
Imports System.Text
Imports System.Threading

Public Class Class2
Public Mycontinue As Boolean = True

    Public Sub FindMyPort()
        Dim storage = PhoneStorageType.Sim
        Dim MsgLocation As Integer
        Dim counter As Integer = 0
        Dim GetManu As String = ""
        Try
            comm = New GsmCommMain(9, 9600)
            comm.Open()
            IsConnected = True
            counter = 0
            Try
                Dim info As IdentificationInfo = comm.IdentifyDevice
                GetManu = info.Manufacturer

            Catch ex As Exception
                Thread.Sleep(6000)
                Debug.Print("error getting manufacutarer")
            End Try

            If GetManu = "huawei" Then
                Try

                    Dim messages As DecodedShortMessage() = comm.ReadMessages(PhoneMessageStatus.ReceivedUnread, PhoneStorageType.Sim)

                    For Each DecodedShortMessage In messages
                        MsgLocation = DecodedShortMessage.Index
                     '   ShowMessage(DecodedShortMessage.Data) 
'just a function to cop to db.  program crashes even if this is never called

                        counter = counter + 1
                        Thread.Sleep(1000)
                        Try
                            comm.DeleteMessage(MsgLocation, PhoneStorageType.Sim)
                        Catch ex As Exception
                            Debug.Print("error deleting from inbox")
                            Mycontinue = False
                            Exit Sub
                            Finally
                            messages = Nothing
                        End Try
                    Next
                Catch ex As Exception
                    Debug.Print("error gettting inbox")
                    Mycontinue = False
                    Exit Sub
                End Try

                If counter > 0 Then
                    NewMsg = True
                End If
            Else
            End If


        Catch ex As Exception
            Debug.Print(ex.ToString)
            IsConnected = False
        End Try
        Try
            comm.Close()
        Catch ex As Exception
            Debug.Print("couldnt close port")
            IsConnected = False

        End Try

        If Mycontinue = True Then
            Debug.Print("start new thread")
            Thread.Sleep(4000)

            Threading.ThreadPool.QueueUserWorkItem(AddressOf FindMyPort)
        Else
            Debug.Print("stopped")
        End If
        storage = Nothing
        GetManu = Nothing
        MsgLocation = Nothing
        counter = Nothing
        GC.Collect()
    End Sub
End Class

[MaximilianMayrhofer]

You need to handle the UnhandledException event of your program and dump the error to a log file. Then post the error message here and we can take a look at it. Do you know how to do this?

[dreamdelerium]

no, i dont. can you give me some pointers?

[dreamdelerium]

ok, i found this in the help file:
To log an unhandled exception
Have a project selected in Solution Explorer. On the Project menu, choose Properties.

Click the Application tab.
Click the View Application Events button to open the Code Editor.
This opens the ApplicationEvents.vb file.
Have the ApplicationEvents.vb file open in the Code Editor. On the General menu, choose MyApplication Events.
On the Declarations menu, choose UnhandledException.
The application raises the UnhandledException event before the main application runs.
Add the My.Application.Log.WriteException method to the UnhandledException event handler.

and then i add this:

My.Application.Log.WriteException(e.Exception, _
    TraceEventType.Critical, _
    "Application shut down at " & _
    My.Computer.Clock.GmtTime.ToString)

heres a stupid question: wheres the log kept at? how do i read it?

also, i saw that theres a setting in the unhandled exception event that can be set so that the app isnt terminated when the event is raised. how do i change this?

[Shaggy Hiker]

On a related note, and possibly because I don't use Vista, are you sure this indicates that your program has thrown an exception? Could it just be hung somewhere?

[dreamdelerium]

i dont know. im knew to all this. this is actually my first program and im just teaching myself. how do i know if its "just hung" and if it is, how do i prevent it from hanging. it happens pretty regularly. i think the problem is comming from one of two places. either the usb modem that im polling is sending some strange output, which im not handling properly (but i dont know what it could be sending) or the the gsmcomm library im using is throwing some exception for some reason. the last thing i can think of is, could i be using up to much resources?

[MaximilianMayrhofer]

Just hung will pop up "Not Responding". "Stopped Working" actually does indicate a crash. And the log file will be in the debug folder of your project.